1. Field of the Invention:
The present invention relates to a polyamide resin composition. More particularly, it relates to a polyamide resin composition having excellent appearance and flameproofing characteristic.
2. Description of the Prior Art:
To flameproof polyamide resin compositions, it has been proposed to add melamine (Japanese Patent Publication No. 1714/1972); to add cyanuric acid (U.S. Pat. No. 3,980,616) or to add both melamine and cyanuric acid (U.S. Pat. No. 4,001,177).
In the case of the addition of melamine, satisfactory flame-proofing effect could not be imparted without adding more than ten wt. parts of melamine to 100 wt. parts of polyamide resin. The melamine sublimes during the molding operation to deposit on the mold, which has been known as plate-out, whereby undesired parting or straining of the molded product are caused. Alternatively, melamine or decomposed material is bled out on the surface of the molded product by aging the molded product for a long time which has been known as the blooming phenomenon. The appearance is disadvantageously inferior.
In the case of the addition of cyanuric acid, the flameproofing effect can be expected by the addition of a smaller amount of cyanuric acid in comparison with melamine. However, the mechanical properties of the molded product are inferior and the blooming phenomenon is disadvantageously severe.
In the case of the addition of both cyanuric acid and melamine, it is necessary to add more than ten wt. parts of a mixture of melamine and cyanuric acid (1:1) to 100 wt. parts of polyamide resin in order to impart a satisfactory flameproofing effect, and plate-out and the blooming phenomena are not small enough to be satisfactory.
The inventors INVENTION worked to overcome these disadvantages.